Write Good Tests With Mocha

Learn to use the Mocha framework and the Node.js assert library to write, automate, and organize tests in Javascript.

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Key Concepts

Review core concepts you need to learn to master this subject

before() Hooks

beforeEach() Hooks

after() Hooks

afterEach() Hooks

Test Frameworks

describe() functions

it() functions

The assert Library

`before()` Hooks

before(() => {
   path = './message.txt';
 });

In a test file, the function before() will be executed first, regardless of it’s placement in the code block. before() is often used to set up code, like variables and values, for other function calls to use in their execution.

Automate and Organize Tests

Lesson 1 of 2

1
Introduction
Testing is an essential part of development. When used properly, testing can catch and identify issues with your implementation code before you deploy it to users. Instead of testing every function…
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2
Install Mocha I
Before writing any tests you’ll need to use Node.js and npm to set up a JavaScript project and install Mocha. - Node allows you to run JavaScript in the terminal - npm is a Node tool that a…
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3
Install Mocha II
After installing Mocha as a dependency we can run it in two ways. The first (and more tedious) method is to call it directly from node_modules: $ ./node_modules/mocha/bin/mocha The second (a…
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4
describe and it blocks
In Mocha we group tests using the describe function and define tests using the it function. These two functions can be used to make your test suite complete, maintainable, and expressive in t…
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5
assert
In the last exercise, you learned how to organize and automate tests using the Mocha test framework. To write the tests themselves, we can use the assert.ok method provided by Node.js. In programm…
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6
Setup, Exercise, and Verify
In this exercise you will be separating a test into setup, exercise, and verify phases. This distinct and well-defined separation of steps makes your test more reliable, maintainable, a…
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7
Teardown
So far, we’ve been writing just one test using a single it() block. However, in most situations, we will need to write many tests for a particular feature that get executed in succession. Running…
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8
Hooks
Over the last two exercises, we learned about the four main phases of a test: setup, execute, verify, and teardown. In the last exercise, you may have noticed that the setup and teardown steps were…
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9
Review
You can now write tests with Mocha and Node’s assert.ok() ! In this lesson you learned to: - Install Mocha with npm - Organize tests with describe() and it() - Ensure your tests are isolated and e…
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